A woman in her 40s has died after being savaged by a dog at a property in south London.The victim suffered multiple injuries and was pronounced dead at the scene, in Wallington, near Sutton.
Scotland Yard said the dog - a Belgian mastiff - was shot dead by police firearms officers.
There was at least one other person at the property at the time of the attack, but no-one else was injured.
A puppy has also been removed from the property in Demesne Road.
Police and paramedics were first called out at 8.57pm on Thursday, following reports of an animal attack.
A post-mortem examination was being arranged and next of kin had yet to be informed. Detectives from Sutton Borough are investigating.
Belgian mastiffs - which can grow to a height of 32 inches (78cm) and weigh as much as 50kg - are not classified as dangerous under the Dangerous Dogs Act.
The law refers to four kinds of dog which are banned: pit bull terrier; Japanese tosa; dogo Argentino; and fila Braziliero.
Belgian mastiffs are said to be "calm and obedient" on website dogbreedinfo.com.
The death in Wallington is the latest in a series of serious dog attacks on humans.
A four-year-old girl was scarred for life in October after being savaged by a Japanese akita dog in Lee-on-Solent, Hants.
In April, 18-month-old Zumer Ahmed died after she was mauled by a cross-breed animal at the family home in Crawley, West Sussex.
In February 2009, three-and-a-half-month-old Jadin Joseph Mech was mauled to death by two family dogs at the home of his grandmother, in Ystrad Mynach, South Wales.
The dogs - a Staffordshire bull terrier and a Jack Russell - were destroyed.
Update December 24, 2010 10:56am - The following article is from Daily Mail:
Police hunt for owner of dog that savaged to death woman, 50, in her home: Officers use riot shields to fight off huge mastiff before shooting it